Requirement of Phosphatidylglycerol for the trimer formation of PS I reaction center

Abstract

It is interesting to know the function of phospatidyl glycerol (PG) molecules bound nearby P700 that were found in the 3D structure of PS I reaction center of cyanobacteria. We destructed the PG-synthetase gene in Synechocystis PCC6803 strain to study the role of PG. In this mutant strain, upon the depletion of PG from the culture medium for 3 days, PS II activity was suppressed at the QB site with slight effect on PS I as reported previously. Longer PG-depletion, however, lead to the loss of PS I reaction center, especially in its trimer form.. Functional features of PS I and II reaction centers were also studied by fluorescence life time spectroscopy at 5-77K and by measurement of delayed fluorescence.